I understood the part where data needs to be migrated from apidb > osmosis > changesetfile > osm2pgsql > PostGIS schema.

However I can't figure out how to generate the changesetfile from osmosis on a regular basis. For example, I am working with a small area in OSM (oberbayern.osm) from geofabrik.de. Both ApiDB and PostGIS have data from the same .osm file with first import.

Now, I am able to upload new data from JOSM to ApiDB. This will happen on a daily basis. How do I keep track of those changes and put them to PostGIS?